1. Having knowledge or cognizance: aware of the difference between the two versions; became aware of faint sound.
2. Archaic Vigilant; watchful.

Synonyms: These adjectives mean mindful or heedful: Aware implies knowledge gained through one's own perceptions or by means of information: Are you aware of your opponent's hostility? I am aware that the legislation passed.
Cognizant is a formal equivalent of aware: "Our research indicates that the nation's youth are cognizant of the law" (Jerry D. Jennings).
Conscious emphasizes the recognition of something sensed or felt: "an importance . . . of which even Americans are barely conscious" (William Stanley Jevons).
Sensible implies knowledge gained through intuition or intellectual perception: "I am sensible that the mention of such a circumstance may appear trifling" (Henry Hallam).
To be awake is to have full consciousness of something: "as much awake to the novelty of attention in that quarter as Elizabeth herself" (Jane Austen).
Alert stresses quickness to recognize and respond: I remained alert to career opportunities.
Watchful and vigilant imply looking out for what is dangerous or potentially so: The watchful parents protected their toddler. The ranger kept a vigilant eye out for forest fires.